Origin of the Hidden Ones

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.) [I] Origin of the Hidden Ones deals 4 damage to any target. [II] Create two 1/1 black Assassin creature tokens with menace. [III] Whenever an Assassin you control attacks this turn, create a 1/1 black Assassin creature token with menace that's tapped and attacking.